A Republican member of Congress in charge of investigating the Benghazi attacks in which four Americans were killed said Monday that questions remain about what happened that night but he does not think the Obama administration formulated a "complete cover-up."

Rep. Lynn Westmoreland, R-Georgia, chair of a House Intelligence subcommittee,said incompetence is the likely culprit. "I don't think they knew what they were doing," he said.

He said the various arms of government involved -- the State Department and intelligence agencies -- "got their communications mixed up."

"I think what ended up happening, you had the State Department trying to tell one story and you had the security, the intelligence community that may have been trying to sell another story," Westmoreland said on CNN's "New Day."

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Westmoreland's subcommittee interviewed five CIA contractors who were at the compound that night.

More than a year after the attack on the U.S. compound in Benghazi, questions still linger as to what led to the deaths of Ambassador Chris Stevens and three other Americans. The House Intelligence Committee has held 15 hearings on the attacks.

In the days following the September 11, 2012, attacks, the Obama administration said the incident was not a planned attack but was a protest turned violent. That story quickly unraveled and the administration has been accused of a cover-up.

"I don't think there was any doubt that they knew it was a coordinated attack," Westmoreland said, pointing to the "accuracy of the mortar fire that came."

More questions about a cover-up arose recently when members of Congress found out that Americans present that night were asked to sign an updated nondisclosure agreement.

CNN investigative correspondent Drew Griffin reported last week that a source told him that "there is not a person in Washington, D.C., who doesn't understand why the forms were put in front of these people."

Westmoreland said it's "not that unusual" to sign updated security agreements and that the forms specifically stated that signatories have the right to speak to House and Senate Intelligence committees.

Westmoreland also said that reports of "an ongoing gun battle" throughout the night are "just not true." He said the CIA operatives told his subcommittee there was random fire throughout the night, which was commonplace in Benghazi.

He said questions do remain, however, including if there was a lull in activity between the sparse gunfire.

In addition, Westmoreland said that when the CIA arrived at the compound that night, regional security forces were unarmed and one officer didn't have his shoes on.

"I think they were totally unprepared for any type of attack," he said.